Electroluminescent lamp panels are used in a wide variety of applications, including automotive displays such as speedometers or the like, marine navigation systems with numerous display dials, backlighting for computer applications and numerous other environments. Electroluminescent lamp panels often are used in membrane or touch switch panels wherein an electroluminescent lamp panel is juxtaposed with a switch panel to form a combination switch-lamp structure, such as in U.S. Pat. Nos. 4,532,395 and 4,683,360.
Basically, an electroluminescent lamp panel includes a base electrode spaced from a transparent electrode together with a dielectric layer and a phosphorescent layer between the two electrodes. Such a basic device converts electricity into light, the conversion taking place inside grains or particles of a phosphor subjected to an alternating electric field. The grains or crystals "glow" when excited by the electric field. Light exits the panel through the transparent electrode near the front of the panel.
One of the major problems with the use of electroluminescent lamp panels in such environments as automotive, marine and like applications is the penetration of moisture into the panel, particularly from the back side thereof. Such moisture penetration greatly reduces the life of the panel.
Another problem affecting the life of the panel is the life of the phosphor particles themselves. As phosphor grains age, metallic dopants, such as copper, in the phosphor migrate to the surface of the grains, causing phosphor darkening.
Still other problems in electroluminescent lamp panels revolve around various shorting propensities.
This invention is directed to a new and improved electroluminescent lamp panel which solves the above problems and which has an extended life not heretofore available.